Feral Herbivores Research Articles

Impacts of feral grazers and unseasonal summer flooding on floodplain carbon dynamics: A case study

Wetlands are amongst the world's most effective natural carbon sinks, and also have the potential to emit large quantities of stored carbon back into the atmosphere if disturbed. In the Murray-Darling Basin, high consumptive demand for water has led to widespread wetland loss and degradation. Remaining wetlands are commonly under additional pressure from grazing and trampling by feral herbivores or livestock and unseasonal flooding in summer to meet peak irrigation demand. Here, during a summer flood in Barmah National Park, we compared soil carbon and nitrogen and carbon emissions within, and outside of, a feral herbivore exclusion plot. The sustained global warming potential from the whole wetland (i.e., both within- and outside of the exclusion plot), totalled from both carbon dioxide (CO2) and methane (CH4) emissions, averaged 132.27 ± 9.88 g CO2-e m−2 d−1, an estimated 28- to 89-fold higher than the global average for natural wetlands. The high warming potential of the wetland was driven strongly by CH4 emissions, which made up over 90% of total CO2-equivalents, with CO2 contributing <10%. We expect these values represent peak CH4 emissions from the site due to high water and soil temperatures, and low water levels, at the time of sampling. Soil carbon and nitrogen did not differ significantly within and outside of the exclusion plot, but surface soil samples indicated recent condition improvement in the absence of feral herbivores. We suggest that an emissions avoidance incentive could be developed around unseasonal, summer watering of forested floodplains where flood timing can be controlled.

Land use and dingo baiting are correlated withthe density of kangaroos in rangeland systems.

Rangelands worldwide have been subject to broadscale modification, such as widespread predator control, introduction of permanent livestock water and altered vegetation to improve grazing. In Australia, these landscape changes have resulted in kangaroos (i.e. large macropods) populations increasing over the past 200 years. Kangaroos are a key contributor to total grazing pressure and in conjunction with livestock and feral herbivores have been linked to land degradation. We used 22 years of aerial survey data to investigate whether the density of 3 macropod species in the southern rangelands of Western Australia was associated with: (i) land use, including type of livestock, total livestock, density of feral goats, type of land tenure, and kangaroo commercial harvest effort; (ii) predator management, including permitted dingo control effort, estimated dingo abundance, and presence of the State Barrier Fence (a dingo exclusion fence); and (iii) environmental variables: ruggedness, rainfall, fractional cover, and total standing dry matter. Red kangaroos (Osphranter rufus) were most abundant in flat, open vegetation, on pastoral land, where area permitted for dingo control was high, and numbers were positively associated with antecedent rainfall with a 12-month delay. Western grey kangaroos (Macropus fuliginosus) were most abundant on flat, agricultural land, but less abundant in areas with high permitted dingo control. Euros (Osphranter robustus) were most abundant in rugged pastoral land with open vegetation, where permitted dingo control was high. While environmental variables are key drivers of landscape productivity and kangaroo populations, anthropogenic factors such as land use and permitted dingo control are strongly associated with kangaroo abundance.

Identifying hypotheses for drivers of decline of the bogong moth (Agrotis infusa)

Context Migratory populations of bogong moths in Australia are in decline. Numbers decreased after European settlement in the 1800s, and were stable before declining again from about 1980. Numerous hypothesised drivers for the decline have been postulated, and Caughley’s declining population paradigm provides a systematic approach to diagnosing which of these are important, and hence the knowledge to guide recovery actions. Aims This paper aims to assess which of the hypothesised drivers remain as candidate hypotheses for further investigation. Methods Within the context of known bogong moth life history and the timing of observed declines, hypothesised drivers of the two decline phases were assessed with respect to their potential impact on larval recruitment and adult survival during migration and aestivation. Key results Changes in vegetation composition and availability arising from the spread of pastoralism stand out as a likely driver of the early decline, with the herbivorous moth larva facing competition with introduced livestock, feral herbivores, and increased densities of native macropods. Many of the numerous postulated drivers of the most recent decline (e.g. changes in rainfall, rising temperatures in aestivation sites, increasing fire frequency) appear to have little support to be retained. Postulated drivers that remain as working hypotheses include increasing soil temperatures, increased cropping areas, and changed cropping practices and area. The effect of some drivers, such as artificial light pollution, is unclear and may warrant further investigation. Conclusions Inference on the drivers of bogong moth population decline is wanting. Implications Designed experiments are needed.

A Hollow Argument: Understory Vegetation and Disturbance Determine Abundance of Hollow-Dependent Mammals in an Australian Tropical Savanna

Native mammals are suffering widespread and ongoing population declines across northern Australia. These declines are likely driven by multiple, interacting factors including altered fire regimes, predation by feral cats, and grazing by feral herbivores. In addition, the loss of tree hollows due to frequent, intense fires may also be contributing to the decline of hollow-dependent mammals. We currently have little understanding of how the availability of tree hollows influences populations of hollow-dependent mammals in northern Australian savannas. Here, we test the hypothesis that the abundance of hollow-dependent mammals is higher in areas with a greater availability of tree hollows. We used camera-trap data from 82 sites across the savannas of Melville Island, the largest island in monsoonal northern Australia. Royle–Nichols abundance-induced heterogeneity models were used to investigate the biophysical correlates of the abundance of three threatened mammals: northern brushtail possum (Trichosurus vulpecula arnhemensis), black-footed tree-rat (Mesembriomys gouldii), and brush-tailed rabbit-rat (Conilurus penicillatus). Our analyses included two variables that reflect the availability of tree hollows: the density of tree hollows, estimated from the ground, and the density of large eucalypt trees (Eucalyptus and Corymbia spp.). We found no evidence that the abundance of the three hollow-dependent mammals is positively associated with the availability of tree hollows on Melville Island. Despite their reliance on hollow-bearing trees for denning, the abundance of these mammals appears to be more strongly associated with other factors, such as the characteristics of the understory (i.e., shrub density), which affords protection from predators (including feral cats) and access to food resources. Future conservation management should aim to maintain a dense, diverse understory by managing fire and feral herbivores to facilitate the persistence of hollow-dependent mammals across northern Australia.

Consequences of the reintroduction of regionally extinct mammals for vegetation composition and structure at two established reintroduction sites in semi‐arid Australia

AbstractAustralia has lost a substantial proportion of its small to medium‐sized mammals since European colonisation. Given the passage of time since local extinctions – decades to more than a century for much of the continent – the consequences of these changes for vegetation are poorly known. In this study, we take advantage of two well‐established mammal reintroduction projects in southern inland Australia to examine the ecological consequences for vegetation of re‐established mammal populations. The study is based on replicated surveys inside and outside fenced reintroduction sites, with treatments characterised by varying presence, absence and composition of reintroduced mammals, feral predators and feral herbivores. We found a suite of differences in vegetation between reintroduction sites and matched controls, with generally lower richness inside reintroduction sites (with one exception). Other compositional differences varied by location, with some functional groups – herbaceous chenopods, shrubby chenopods, introduced geophytes and low shrubs – and a few individual chenopod species – being less frequent inside the reintroduction site at one location. At the same site, mistletoes and orchids were less abundant inside than outside the reintroduction site. Structural differences included a higher percentage of bare ground inside, and a higher ground layer for one inside treatment versus outside. Although the absence of baseline data and replicated temporal data limits inference as to causal factors, many of the results are consistent with data from other reintroduction sites. Some results, especially those for geophytes, mistletoes and some chenopods, may indicate long‐term consequences for those taxa. Whilst predator‐fencing substantially contributes to prevention of extinction of highly threatened mammals, some environmental trade‐offs are inevitable. Nonetheless, given the aims of reintroductions include re‐constructing natural ecosystem processes, the resulting changes to vegetation require ongoing investigation and further monitoring.

Restoring cultural plant communities at sacred water sites

ABSTRACT Water places have been critical to central Australian Indigenous peoples for thousands of years. However, many waterhole communities have been degraded by factors including invasion by large feral herbivores and non-native plants. We document the restoration of two waterholes near Santa Teresa (Ltyentye Apurte), with a focus on culturally significant plants. We described plant communities around waterholes in 2007, before fences were erected to exclude large feral animals, and again in 2018. Plant cover and diversity were higher after fencing and the occurrence of culturally significant plants greatly increased. However, invasive buffel grass was the dominant ground cover after fencing and will require active suppression to allow culturally significant native plants to proliferate. Traditional Owners identified excellent opportunities to achieve restoration through educating young people, with a focus on sharing intergenerational knowledge and engaging local Indigenous rangers in management, enabling them to meet the traditional obligations to care for country.

Variation in feral cat density between two large adjacent islands in Australia’s monsoon tropics

Despite contributing to the ongoing collapse of native mammal populations across northern Australian savannas, we have limited understanding of the ecological constraints of feral cat population density in this system. Addressing such knowledge gaps is a crucial step towards mitigating the impacts of feral cats, and is particularly important for the large islands off northern Australia that remain as strongholds for numerous species vulnerable to cat predation. Here, we investigated cat density across Melville and Bathurst Island, two large islands in Australia’s monsoon tropics. We deployed large grids (~13 km2) of 70 camera-traps at four locations to investigate how feral cat density varies under different combinations of fire frequency, and feral herbivore presence. Using spatially-explicit capture-recapture models, we estimated feral cat density on Melville Island to be 0.15 cats km−2. We did not record any cat detections on Bathurst Island. Using simulations, we predicted that if cat density on Bathurst Island was equal to that on Melville Island, we would have expected to record 27.9 detections of 9.9 individual cats. Our results, coupled with other recent surveys, suggest that the density of cats is much lower on Bathurst Island than the adjacent Melville Island. The absence of feral herbivores on Bathurst Island may have contributed to this variation in cat density. Management that enhances understorey vegetation density, through feral herbivore control, as well as fire management, could help mitigate the impact of feral cats on northern Australian savanna biodiversity.

Variation of Hematochemical Profile and Vitamin E Status in Feral Giara Horses From Free Grazing in the Wild to Hay Feeding During Captivity

Wildlife protection and management are important priorities for landscape identity and biodiversity preservation. Feeding practices of fauna confined in facilities during temporary captivity are fundamental to support animal health and natural behavior. Appropriate provision of feedstuffs appears to be necessary to support the best practices in respect of animal species-specific natural diet. This investigation explored the variation of the metabolic profile by means of selected metabolite and respective circulating levels in a group feral Giara horses undergoing the change of the diet, moving from natural free grazing in the wild to temporary captivity. Six Giara horses (4 mares and 2 stallions; estimated age: 2.5–3 years; body weight: 163–170 kg) were captured to monitor the serological reaction to equine infectious anemia (EIA; screening at Coggins test). Animals were sheltered in a wildlife rescue center for a duration of 4 weeks, and all received the same hay-based diet (ad libitum). On 0 and 28 days of captivity, blood serum alpha-tocopherol (α-TOH) concentration was determined alongside selected metabolites (liver enzymes, total protein and fractions, cholesterol, triglycerides, and macrominerals and trace elements). Comparative feces quality and composition were also assessed. Both serum samples (0 vs. 28 days) displayed α-TOH levels below (<2 μg/mL) adequacy established for the domestic horse. Initial levels markedly (P = .020) decreased after the 4 weeks of captivity (Δ = −32.5%). Vitamin E status and ALT levels varied significantly, but serum protein fractions did not point to significant variations before and after captivity. All horses tested negative to EIA. Monitoring of vitamin E status of wild and feral herbivores may be recommendable in the context of adequate feeding practices during captivity to prevent potential deficiency or excessive depletion.

Bottom-up and top-down processes influence contemporary patterns of mammal species richness in Australia's monsoonal tropics

In recent decades severe mammal declines have occurred in the vast and uncleared tropical savannas of northern Australia. Mounting evidence suggests that feral cats (Felis catus), large feral herbivores and increased frequency of high-severity fires, are all contributing to declines; however, the respective influence of each threat remains unclear. There is an urgent need to quantify the relative impacts of both ‘bottom-up’ (i.e. the depletion of resources and habitat simplification from contemporary disturbance regimes) and ‘top-down’ (i.e. increased predation pressure) factors on small mammal populations to inform where, and how, remedial conservation efforts should be targeted in northern Australia. We conducted an extensive survey of mammals across ca. 370,000 km2 of monsoonal northern Australia using both camera-trapping and live-trapping methods. From multispecies occupancy models, we found that feral herbivore abundance, dingo abundance and feral cat occupancy were the best predictors of species richness of small (<5500 g) mammals, with species richness declining as the respective pressures increased. Our results highlight that underlying productivity has seemingly enhanced the capacity of native mammals to withstand pressures, as species that have severely declined are now more likely to occur in areas with greater productivity. We suggest that a disturbance-driven reduction in habitat complexity and productivity has significantly disrupted bottom-up processes in northern Australia, subsequently increasing top-down pressure from predation, causing severe declines across much of the native mammal assemblage. Without maintaining, enhancing or recovering habitat condition in this region, long-term conservation and recovery of mammal diversity is unlikely.

Distribution and abundance of large herbivores in a northern Australian tropical savanna: A multi‐scale approach

AbstractAustralian mammals have exhibited exceptionally high rates of decline since European settlement 230 years ago with much focus on small mammals in northern tropical savannas. In these systems, little scientific attention has been given to the suite of grazing macropods, family Macropodidae, (common wallaroo (Osphranter robustus), antilopine wallaroo (O. antilopinus) and agile wallaby (Notamacropus agilis)). These species may be impacted by feral herbivores and contemporary fire regimes, two threats linked to small mammal declines. A multi‐scale approach using aerial surveys, road surveys and camera trapping was utilised to determine the effects of feral cattle and fire on the distribution and abundance of large macropods in the North Kimberley bioregion. Feral cattle density and biomass exceeded that of macropods regardless of survey technique. Density estimates for cattle were up to 125 times higher (0.3–10.0 km−2) than estimates for macropods (0.08–0.49 km−2). Cattle biomass, based on the aerial survey estimates (corrected for perception bias), were 15 and 95 times higher than macropods for infertile (279 vs. 19 kg km−2) and fertile savannas (518 vs. 5 kg km−2), respectively. Proximity to the nearest pastoral station was a significant predictor of the aerial sightings of feral cattle (P ≤ 0.05). Abundance and foraging activity of cattle were positively associated (P ≤ 0.05) with recently burnt areas. In contrast, camera trapping showed agile wallaby and wallaroo occurrence and foraging were associated with longer unburnt areas (P ≤ 0.05). Agile wallaby and wallaroo were negatively associated with cattle (P ≤ 0.05) and showed substantial diurnal and seasonal separation consistent with an antagonistic interspecific interaction. Results also suggest that the agile wallaby is the primary prey of the dingo, not wallaroo. Collectively, this study suggests that recent landscape changes such as altered fire regimes and introduced herbivores have negatively impacted large grazing macropod species.

Feral cats are more abundant under severe disturbance regimes in an Australian tropical savanna

Abstract ContextThere is an increasing awareness that feral cats play a key role in driving the ongoing decline of small mammals across northern Australia; yet, the factors that control the distribution, abundance and behaviour of feral cats are poorly understood. These key knowledge gaps make it near-impossible for managers to mitigate the impacts of cats on small mammals. AimsWe investigated the environmental correlates of feral cat activity and abundance across the savanna woodlands of Melville Island, the larger of the two main Tiwi Islands, northern Australia. MethodsWe conducted camera-trap surveys at 88 sites, and related cat activity and abundance to a range of biophysical variables, either measured in the field or derived from remotely sensed data. Key resultsWe found that feral cat activity and abundance tended to be highest in areas characterised by severe disturbance regimes, namely high frequencies of severe fires and high feral herbivore activity. ConclusionsOur results have contributed to the growing body of research demonstrating that in northern Australian savanna landscapes, disturbance regimes characterised by frequent high-severity fires and grazing by feral herbivores may benefit feral cats. This is most likely to be a result of high-severity fire and grazing removing understorey biomass, which increases the time that the habitat remains in an open state in which cats can hunt more efficiently. This is due to both the frequent and extensive removal, and longer-term thinning of ground layer vegetation by severe fires, as well as the suppressed post-fire recovery of ground layer vegetation due to grazing by feral herbivores. ImplicationsManagement that reduces the frequency of severe fires and the density of feral herbivores could disadvantage feral cat populations on Melville Island. A firm understanding of how threatening processes interact, and how they vary across landscapes with different environmental conditions, is critical for ensuring management success.

Persistence of the broad-toothed rat (Mastacomys fuscus) across Victoria is correlated with climate and elevation

Abstract ContextThe broad-toothed rat (Mastacomys fuscus; BTR) is distributed throughout south-eastern Australia, but its populations are restricted and dispersed. BTRs prefer cooler, wetter habitats and, as such, future climate change is projected to lead to further range reductions. However, recent changes in its distribution have not been well documented, and there is limited knowledge about the current occupancy and population size of the species in Victoria. AimsTo evaluate recent historical changes in the distribution of BTRs in Victoria, and to test whether changes in distribution are correlated with climate and elevation. MethodsWe obtained all documented records of BTRs in the state before 1990 and used field notes and verbal descriptions to geo-reference their historical localities. We then used a repeated sampling design to resurvey all historically occupied sites with a geographic coordinate uncertainty of 4km or less. We tested for the effects of climate and elevation on the persistence of BTRs. Key resultsWe detected BTRs at 32 of 68 historical sites surveyed. Consistent with climate model predictions, site persistence was more likely to occur at sites of higher elevation and precipitation and less likely to occur at sites with a higher temperature. Minimum temperature of the coldest month was the single best predictor of persistence. ConclusionsThese results demonstrated a substantial decline in the persistence of BTRs at historical sites across Victoria and provided a benchmark for future monitoring and management efforts. ImplicationsThe decline of BTRs from historically occupied sites across Victoria is consistent with their listing as endangered in the state, and climate correlations suggest further declines, with projected climate change compounding other threats to the species such as introduced predators, feral herbivores, fire and land use. However, the status of BTRs in Victoria and understanding of the threats to their persistence are based on sparse data, highlighting the critical need for more effective monitoring of the species.

The impact of camel visitation on native wildlife at remote waterholes in arid Australia

AbstractInvasive species can impact their new environments in different ways, including through exploitation competition and interference competition. For the past decade we have documented the severe degradation of central Australian waterholes by feral camels. Not surprisingly, large feral herbivores can have profound negative impacts on aquatic biodiversity. Less understood was the extent that feral camels impact on native terrestrial wildlife for access to water. From 2011 to 2013 we used camera traps at six waterholes in central Australia to document the co‐occurrence of feral camels and some native wildlife. We used circular statistics and univariate analyses to evaluate activity budgets, visitation frequency and species co‐occurrence for camels, dingoes and bird species that require daily or regular access to water. When camels were present, birds and dingoes visited waterholes less frequently than on days camels were absent. The daily activity budget of birds shifted when camels and dingoes were present, and dingo activity shifted when camels were present. Although the temporal overlap of camels and birds was low, it was not less than expected by chance. Our data suggest that feral camels are the superior resource exploiter at these arid waterholes and reduce wildlife visitation and alter activity budgets. It remains to be tested whether this translates to longer‐term impacts on native birds and dingoes.

Total grazing pressure - a defining concept for extensive pastoral systems in the southern rangelands of Australia

In Australia, particularly in the southern rangelands, large populations of native and feral herbivores (including kangaroos, goats, rabbits, pigs, donkeys and camels, depending on the location) co-exist with domestic livestock. In recent decades the concept of ‘total grazing pressure’ has been developed, and widely accepted, to denote the total forage demand of all vertebrate herbivores relative to the forage supply. This concept provides a framework within which both domestic and non-domestic species can be managed to allow commercially viable livestock production, landscape maintenance or restoration and species conservation. The concept should have relevance wherever pest animal control programs, biodiversity conservation, or commercialisation of wildlife are conducted in conjunction with extensive livestock production. The rationale for the compilation of the Special Issue is outlined.

Rotational grazing management achieves similar plant diversity outcomes to areas managed for conservation in a semi-arid rangeland

Despite the increasing extent of protected areas throughout the world, biodiversity decline continues. Grazing management that promotes both biodiversity and production outcomes has the potential to improve broad-scale conservation and complement the protected area network. In this study we explored the potential to integrate commercial livestock grazing and conservation in a semi-arid rangeland in south-eastern Australia. Understorey floristic composition and diversity were compared at different spatial scales across three grazing management treatments: (1) continuous commercial grazing management where paddocks were grazed for the majority of the year (≥8 months per annum); (2) rotational commercial grazing management where livestock are frequently rotated and paddocks rested for &amp;gt;4 months per annum; and (3) protected areas managed for conservation with domestic livestock excluded and grazed only by native and feral herbivores. The season of sampling, rainfall, soil characteristics and the spatial location of sites were the dominant drivers of variability in understorey plant species composition; the effect of grazing treatment on understorey plant species composition was relatively minor. However, areas managed for conservation and under rotational forms of commercial grazing management generally had greater floristic richness and diversity than continuously grazed areas, the results varying with season (spring/autumn) and soil type (clay/sandy-loam), particularly at fine scale (1-m2 quadrats). These findings indicate that rotational grazing management on commercial properties has the potential to improve biodiversity conservation outside the reserve system compared to conventional grazing management.

The legacy of pasture improvement causes recruitment failure in grassy eucalypt woodland conservation reserves in the Midlands of Tasmania

Australia’s most fragmented and least reserved landscapes are the grassy eucalypt woodlands of the south-east. Two hundred years of agricultural disruption have transformed these landscapes, and agricultural enterprises continue to expand and develop, meaning the threats to these landscapes have not abated. The Tasmanian Midlands is primarily privately owned, with very little area devoted to conservation of biodiversity. In this landscape, conservation covenants have been enacted on many private properties with the intention of encouraging tree recruitment and conservation of threatened plant communities and rare species. Evidence of the effectiveness of these covenants in protecting overstorey tree population health is lacking. This study compared the demographic structures of overstorey Eucalyptus species and midstorey tree genera on public and private properties with contrasting land use histories. Reserves on private lands had little tree recruitment, probably because exotic pasture species were common, whereas tree recruitment was abundant in public reserves, where pasture improvement has not occurred. Active measures are needed to restore ecological structure and function in grassy woodland conservation reserves on private land by encouraging regeneration of Eucalyptus and Acacia species as well as returning the ground layer to a functionally native state. This will entail reinstating fire disturbance, reducing exotic pasture species cover and managing domesticated, feral and native herbivores.

Feral horse impacts on threatened plants and animals in sub‐alpine and montane environments in Victoria, Australia

SummaryFeral herbivores are a major driver of biodiversity loss globally and can alter the structure, composition and functioning of ecosystems. The direct impacts of feral herbivores on plant communities are well studied, but the direct and indirect effect they have on wildlife is not well understood. In Victoria (south‐eastern Australia), a large feral Horse (Equus caballus) population coincides with highly sensitive and nationally endangered Alpine Sphagnum Bogs and Associated Fens communities, and several threatened animal species. We assessed the impact of feral horses on this ecological community and the Alpine Water Skink (Eulamprus kosciuskoi) and the Broad‐toothed Rat (Mastacomys fuscus) at 20 sites with varying levels of horse disturbance. We used scat counts to determine an index of feral horse abundance and quantified impacts associated with their presence in the landscape. Active searches were used for Alpine Water Skink and scat and runway surveys for Broad‐toothed Rat. We also measured the vegetation structure and the abundance of different vegetation types (life forms). Our results suggest that feral horses are associated with vegetation types and characteristics that negatively influence the presence or abundance of Alpine Water Skink and Broad‐toothed Rat. Sites with high horse activity had more low‐growing forbs, and the abundance of Alpine Water Skink was negatively related to this vegetation type. Grasses, sedges, rushes and shrubs were also less dense and lower in height in high horse activity sites, and Broad‐toothed Rat was less likely to be present in areas with these habitat attributes. We recommend that feral horses are controlled to protect these threatened vertebrate species and their Sphagnum bog habitat.

Social return on investment: application for an Indigenous rangelands context

Social Return on Investment (SROI) is an internationally recognised methodology used to measure and value the economic impact of program outcomes. Like a traditional cost-benefit analysis, SROI examines economic outcomes, but also includes the social, environmental and cultural outcomes created by the investment. These outcomes are evaluated against their cost, using financial proxies to estimate their relative economic worth. SROI is particularly valuable in the indigenous natural resource management context, because of the strong ‘value’ or importance of non-economic (particularly cultural) costs and benefits. The Alinytjara Wilurara Natural Resources Management Board undertook a study of the economic, social, environmental and cultural impacts and benefits of the presence of large feral herbivores in the Anangu Pitjantjatjara Yankunytjatjara (APY) Lands, in the far north-west of South Australia. Camels, donkeys and horses present significant impacts for the community in terms of vehicle collisions, community health, damage to infrastructure and water pollution, as well as impacts on sites of cultural and spiritual significance to the local communities. With the annual cost impacts incurred by society caused by large feral herbivores in the APY lands valued at $4.2million and possible dollar value of those animals valued at $140000, the study found that there was a net cost impact of ~$4million from not managing the impact of these animals. The study also found significant cultural impacts of large feral herbivores, such as the fouling of natural springs and other culturally sensitive sites, and further analysis would be required to determine the economic cost of these impacts. Investment models that consider a broad range of costs and benefits are considered necessary for Australian rangelands, particularly Indigenous-owned land. This paper presents a case study of the development of a ranger program that employs local community members to manage the impacts of large feral herbivores that will provide a net benefit to society of ~$3million every year, aside from the additional benefits of employment and economic participation. The $3-million net benefit accrues from saving human lives and costs associated with vehicle accidents, and reduced management costs and increased income for pastoral areas of the APY Lands. APY community members, and the APY Pastoral business are core beneficiaries; however, there are several external beneficiaries that this SROI approach recognises including the Motor Accident Commission, Health Departments and South Australian Police. The strongly positive SROI in this case presents an excellent co-investment opportunity for agencies whose core focus is on road safety and health. Importantly, the SROI approach to creation of social value can be implemented in a way that is consistent with stated community aspirations for development.

Improving ground cover and landscape function in a semi-arid rangeland through alternative grazing management

The development and adoption of sustainable grazing strategies is important to improve the functionality and productivity of agricultural landscapes. Alternative grazing systems incorporating periods of planned rest may achieve this compared to continuous grazing systems, but the evidence is conflicting. Using paired paddock contrasts, soil characteristics, ground cover and landscape function (i.e. soil stability, nutrient cycling, infiltration and landscape organisation indices) were compared between alternative grazing management (incorporating periods of rest), traditional (continuous) grazing, and areas managed for conservation (ungrazed by commercial livestock but grazed by native and feral herbivores) on contrasting soil types in semi-arid rangelands. Relationships between the response variables and understorey floristic biodiversity measures were also explored. Total ground cover was greater under conservation management than grazing, and was greater under alternative grazing than traditional grazing management. Indices of landscape function, including stability, nutrient cycling, patch area and landscape organisation were significantly greater, and interpatch length significantly shorter, under conservation compared to traditional grazing management. Alternative grazing management had intermediate values of landscape function which did not differ significantly to traditional grazing or conservation treatments. Ground cover and floristic biodiversity measures were often positively correlated, but there was no clear relationship between most landscape function and plant biodiversity indices. Landscape function may be important in detecting changes in rangelands that remain undetected by floristic diversity measures. Alternative grazing strategies incorporating planned rest have the potential to improve ground cover with the associated benefits of improved productivity and landscape function compared to continuous grazing regimes.

Bulldozers and Blueberries: Managing Fence Damage by Bare-Nosed Wombats at the Agricultural–Riparian Interface

Fence damage by bare-nosed wombats (Vombatus ursinus) can be a serious problem for farmers wishing to reduce herbivory by other herbivores on valuable crops. We investigated the effectiveness of exclusion fencing to prevent the incursion of unwanted native and feral herbivores and the use of swinging gates designed to allow wombats to pass through the fence without having to damage it. We also examined the temporal response of animals toward exclusion fencing and wombat gates. The 10-month study took place on the interface between natural riparian vegetation and a 22-ha blueberry (Vaccinium corymbosum) orchard in southeastern Australia. Following the testing of exclusion fencing (i.e., footing wire and flexible fence), we installed 6 swinging wombat gates at existing breach points within the exclusion fencing. Wombat gates were 0.6 m high × 0.5 m wide and constructed of 200 × 100 × 6 mm galvanized steel. We continually observed the response of wombats and other animals to both exclusion fencing and wombat gates using heat- and motion-sensing digital cameras. We made a total of 1,480 detections of the 3 target species—wombats, red foxes (Vulpes vulpes), and swamp wallabies (Wallabia bicolor)—in the study area between August 2007 and June 2008. Most were wombat detections (79%), followed by detections of swamp wallabies (12%) and foxes (8%). Wombats became accustomed to using the gates within 1 month, with an average exclusion rate of 48% in the first month after their installation. For the final 6 months of the project, the number of wombat detections showed an exclusion rate of approximately 25%. The swinging gates were equally consistent in excluding foxes and wallabies. The results of this study showed that swinging wombat gates were effective in regulating access by wombats while excluding other unwanted animals.